Risen (or, should I say Oh Pry, I presume?)-
I think you missed big chunks of the post.
People don't pair-bond and enter into romantic unions due to social pressure. This is highly normal, near-ubiquitous human behavior.
Dan Blizerian is getting married now... and it is not because women on Instagram shamed him for his lifestyle. Nor is that the reason most people marry (celebrities and non-celebrities alike).
Your own background of rebelling against a strict upbringing likely clouds that from you. Most people aren't you -- they aren't dealing with a huge amount of social pressure. When they enter into a long-term pair-bond, it is because they desire it.
Lamenting the lack of camaraderie among players also misses this point. People grow. Things they do to go from one stage of life to another they don't continue with in the later stages. There is a lot of broken continuity in most people's lives.
You can have camaraderie among a military unit. But once the unit is no longer serving together, the soldiers from that unit grow apart. They'll still be friends, brothers... but they see each other once a year and barely keep in touch.
Having a group of party friends is like this. You and your boys all go out because you're single and want to (ultimately) get laid. Or at least they do (for you, I know, it is something different).
One by one your buddies are going to find girls they like more than the others, and decide they want to keep those girls. And once they have them, the motivation to go out isn't there anymore.
You have a strong need for social acceptance, which drives you out to nightlife and partying. People who have already passed that stage (which is most people by 30) do not have that same driver. They also don't have the sex (men) or attention (women) drivers they once had. So partying loses its appeal.
That said, there are exceptions. But any normal friend group, the friends are going to drop off one-by-one as they age. They pair up, and stop wanting to go out.
You're still their friend. Maybe their brother. But going out to party is just too costly an activity. They might do it once in a blue moon for the sake of showing their brother some love, but sacrificing their nights, spending a bunch of money, getting trashed and feeling awful the next day, waking up late for work or whatever else they have going on, and putting strain on their relationship by going out with their bachelor party friend to somewhere that explicitly exists for people to meet singles and hook up is a very costly activity for them. No matter how much they love you, they just cannot do it all that much. They get nothing out of it, aside from seeing you, their friend, and sacrifice much.
Here's an idea: if the camaraderie is what's truly important to you, why not make a shift?
Men in relationships maintain friendships too. They just engage in activities less costly to their lives or relationships.
For instance, I'll bet if you put together a barbecue on a Sunday afternoon and invited all your old going-out buddies and their girlfriends/wives, they'd love it... it could even be a regular thing.
Ultimately, it is a little ironic to me that you want them to, in effect, sacrifice their own personal happiness, relationships, and productivity to come out with you, lamenting their lack of camaraderie with you... which ultimately, if they heard you say that, would amount to you socially pressuring them to do something they don't want.
I think the truth is you don't really care about camaraderie at all... if I understand it right.
You'd have no interest in, say, that weekly Sunday barbecue with your old pals and their women.
What you want is an image... this image of the cool guy living the Instagram lifestyle... something other people are going to look at and feel jealous... where they are going to look at you and say "Whoa, what a cool guy that is."
And the thing to realize there is that that is a strong motivator for you to go to party places, but the people you are meeting mostly do not have that motivator.
In fact, the people you most want to hang around will all think that motivation for partying is lame.
I know it's something you're trying to work through.
But I'd perhaps meditate on that a bit.